Introduction: Some of the basic features of animal communications systems have been well known and documented for some time Recently (Hazlett & Estabrook, 1974b; Rubenstein & Hazlett, In Press), we showed that more information is apparently transmitted from the eventual loser of an agonistic interaction to the eventual winner than vice versa. This is, one can predict more about the winner's responses to the eventual loser's behavior than one can about the loser's responses to the eventual winner's behavior. This was true whether the eventual winner was the initiator of an interaction or not. The experiments to be done would test to see if this difference in information transfer is actually causative in an animal's winning or losing a fight, i.e. does an animal win because it responded more "accurately" to the behavior of its opponent. We would thereby take advantage of the analytical power of a particular mathematical technique (character analysis) to analyze a feature of animal communication which was not previously recognized. This would be the logical extension of our earlier results and is part of continued efforts to understand the dynamics of animal communication. Specific Aims: The specific aim of the project is to test the hypothesis that an animal wins an agonistic interation, in part, because it responds (on the average) more predictably to the behavior of its opponent. Methods: In the initial character analysis study of communication in hermit crabs (Hazlett & Estabrook, 1974b),the data were gathered and analyzed without regard to the individual identity of the crabs. Thus the observed result of higher apparent information transfer from loser to winner could be the result of two alternative explanations. It is possible that winners have a somewhat fixed sequence of behavior patterns that are characteristic of and causative in winning. Such sequences have been reported in lobsters Alternatively, the winner gains an advantage not by executing particular "winning" patterns, but by responding (in a predictable way) to the actions of the eventual loser. Thus an animal that appears (from its behavior) to "pay more attention" to the actions of its opponent may have an advantage in agonistic interactions. In an attempt to clarify the mechanism underlying the observed result, individual hermit crabs would be fol (Text Truncated - Exceeds Capacity)